Gerard Pique has criticised referee Fernandez Borbalan, who he felt should have given two penalties in Barcelona's favour, as the Catalan side were beaten 2-1 by Athletic Bilbao in the Copa del Rey on Thursday.
The Spain international also felt that the only reason Athletic were able to beat Barca was by fouling, as the hosts ended the match with just nine players.
Barca will now have to come from behind when the two sides meet in next week's second leg at Camp Nou to reach the quarterfinal, but Pique feels they should be going into that game on level terms.
Xabier Etxeita's foul on Neymar was not given as a penalty, nor was Gorka Iraizoz's clash with Pique as Athletic held on to a narrow win at San Mames.
"There's a clear penalty on Neymar and mine with the goalkeeper is a penalty, too," Pique said after the game in Bilbao.
"But, well, we know how this works. We want to play football and not roulette, which is what provokes these referees. We saw [Real] Madrid against Sevilla the other day. I hope [referees] improve their level."
Pique admitted Barcelona were not at their best in the first half, but he was happy with the improvement he saw after the break.
Lionel Messi's free kick cancelled out first half goals from Aritz Aduriz and Inaki Williams, but the Blaugrana were unable to find another goal, despite late red cards for Raul Garcia and Andre Iturraspe.
According to Pique, the two dismissals are evidence that Ernesto Valverde's side could only stop Barca by fouling them.
"In the first half we weren't at our best and they took advantage of their chances," Pique said. "After that we improved and were better.
"If they've ended the game with nine men it's because they could only stop us through fouls. It's a shame we couldn't draw, but the tie is open. I'm optimistic."
Midfielder Ivan Rakitic was also dismissive of Borbalan's performance.
The Croatian said: "When the referee sees the game [again] I think he will realise he did not have his best night tonight. I don't like to talk about referees, but players have bad games, too."
Barca captain Andres Iniesta was less critical of the referee, but did hint that he was not satisfied with some of the decisions given in the game.
"Sometimes referees get things right, sometimes they don't," he said. "But it was an intense game, like it always is at San Mames."